The present disclosure relates to an electrochemical device including a built-in chargeable/dischargeable storage element.
In an electrochemical device, an electrolyte serves as a conduction path between positive and negative electrodes and as an ion supply source for capacitance generation. Therefore, lack of the electrolyte means malfunction of the electrochemical device. Thus, the electrochemical device needs to be structured to retain the electrolyte for a long time in order to enhance long-term reliability.
In general, the electrochemical device including the chargeable/dischargeable storage element is provided with a hermetically sealed container. The container houses, together with the electrolyte, the storage element including a positive electrode, a negative electrode, and a separator provided between the positive and negative electrodes.
For example, Japanese Patent Application Laid-open No. 2008-211056 (hereinafter, referred to as Patent Document 1) describes an electrochemical element including a container and a sealing plate having a projection that is to be fitted into an opening of the container. In this electrochemical element, the projection has a guide function, which facilitates positioning of the sealing plate with respect to the container. Therefore, when the sealing plate is seam-welded to the container, sealing properties are improved.
Meanwhile, Japanese Patent Application Laid-open No. 2006-128080 (hereinafter, referred to as Patent Document 2) describes an electric double-layer capacitor. The electric double-layer capacitor includes a substrate made of ceramic, which houses positive- and negative-electrode plates and an electrolyte, and a plate-like cover joined to the substrate. The substrate has a bottom surface warped so as to upward project and the cover is warped so as to downward project. In this electric double-layer capacitor, it is possible to securely fix inner components within the container.